/*
 * Copyright 2002-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.transaction.reactive;

import java.util.Collection;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import org.springframework.aop.scope.ScopedObject;
import org.springframework.core.InfrastructureProxy;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;

/**
 * Utility methods for triggering specific {@link TransactionSynchronization}
 * callback methods on all currently registered synchronizations.
 *
 * @author Mark Paluch
 * @author Juergen Hoeller
 * @see TransactionSynchronization
 * @see TransactionSynchronizationManager#getSynchronizations()
 * @since 5.2
 */
abstract class TransactionSynchronizationUtils {

    private static final Log logger = LogFactory.getLog(TransactionSynchronizationUtils.class);

    private static final boolean aopAvailable = ClassUtils.isPresent(
            "org.springframework.aop.scope.ScopedObject", TransactionSynchronizationUtils.class.getClassLoader());


    /**
     * Unwrap the given resource handle if necessary; otherwise return
     * the given handle as-is.
     *
     * @see InfrastructureProxy#getWrappedObject()
     */
    static Object unwrapResourceIfNecessary(Object resource) {
        Assert.notNull(resource, "Resource must not be null");
        Object resourceRef = resource;
        // unwrap infrastructure proxy
        if (resourceRef instanceof InfrastructureProxy) {
            resourceRef = ((InfrastructureProxy) resourceRef).getWrappedObject();
        }
        if (aopAvailable) {
            // now unwrap scoped proxy
            resourceRef = ScopedProxyUnwrapper.unwrapIfNecessary(resourceRef);
        }
        return resourceRef;
    }


    /**
     * Actually invoke the {@code triggerBeforeCommit} methods of the
     * given Spring TransactionSynchronization objects.
     *
     * @param synchronizations a List of TransactionSynchronization objects
     * @see TransactionSynchronization#beforeCommit(boolean)
     */
    public static Mono<Void> triggerBeforeCommit(Collection<TransactionSynchronization> synchronizations, boolean readOnly) {
        return Flux.fromIterable(synchronizations).concatMap(it -> it.beforeCommit(readOnly)).then();
    }

    /**
     * Actually invoke the {@code beforeCompletion} methods of the
     * given Spring TransactionSynchronization objects.
     *
     * @param synchronizations a List of TransactionSynchronization objects
     * @see TransactionSynchronization#beforeCompletion()
     */
    public static Mono<Void> triggerBeforeCompletion(Collection<TransactionSynchronization> synchronizations) {
        return Flux.fromIterable(synchronizations)
                .concatMap(TransactionSynchronization::beforeCompletion).onErrorContinue((t, o) ->
                        logger.error("TransactionSynchronization.beforeCompletion threw exception", t)).then();
    }

    /**
     * Actually invoke the {@code afterCommit} methods of the
     * given Spring TransactionSynchronization objects.
     *
     * @param synchronizations a List of TransactionSynchronization objects
     * @see TransactionSynchronization#afterCommit()
     */
    public static Mono<Void> invokeAfterCommit(Collection<TransactionSynchronization> synchronizations) {
        return Flux.fromIterable(synchronizations)
                .concatMap(TransactionSynchronization::afterCommit)
                .then();
    }

    /**
     * Actually invoke the {@code afterCompletion} methods of the
     * given Spring TransactionSynchronization objects.
     *
     * @param synchronizations a List of TransactionSynchronization objects
     * @param completionStatus the completion status according to the
     *                         constants in the TransactionSynchronization interface
     * @see TransactionSynchronization#afterCompletion(int)
     * @see TransactionSynchronization#STATUS_COMMITTED
     * @see TransactionSynchronization#STATUS_ROLLED_BACK
     * @see TransactionSynchronization#STATUS_UNKNOWN
     */
    public static Mono<Void> invokeAfterCompletion(
            Collection<TransactionSynchronization> synchronizations, int completionStatus) {

        return Flux.fromIterable(synchronizations).concatMap(it -> it.afterCompletion(completionStatus))
                .onErrorContinue((t, o) -> logger.error("TransactionSynchronization.afterCompletion threw exception", t)).then();
    }


    /**
     * Inner class to avoid hard-coded dependency on AOP module.
     */
    private static class ScopedProxyUnwrapper {

        public static Object unwrapIfNecessary(Object resource) {
            if (resource instanceof ScopedObject) {
                return ((ScopedObject) resource).getTargetObject();
            } else {
                return resource;
            }
        }
    }

}
